Electromagnet



Juiy 17, 3,923'. 1,462,129

E. B. THURSTON ELECTROMAGNET Filed Sept. SO 1921 INVENT [l fwn;

Patented July 17, 1923,

UNlTED STA ERNEST B. THURSTON, 01E' TOLEDO, OHIG,

LSSIGNGR TO THE F'AUGI. EON ELEVTUR 8c .MACHINE CO., OF TOLEDO, GHO, i; CORPORATICN Ol OrO;

Application filed September To all w/tofnt it may conce/ru.'

lle it known that l, llnxits'r B. 'l`uuns'roN, a citizen of the United States of America, residing at Yl`oledo, Lucas County, Ohio, haveI invented new and useful Electromagnets, of which the 'following is a spccilicw tion.

This invention relates to electroniagnets.

This invention has utility when incorporated in alternating current electromagnets of the polyphase type.

Referringv to the drawings:

Fig'. l is a side elevation oi' an embodiment of the invention vin a polyphase electrornagrnet; cert-ain parts beine broken away;

'Figa 2 is an end elevation oil the electroinagnet, diagraniniatically indicatinpY the arrangement oi these stator coils; Fig. l shows various characteristic curves includinp the ones described in this specification; and Figi'. 4 is a detail view on an enlarged scale showH ing the laminated plunger in section and the -taper thereoiI as extending only partially there along.

The structure is shown as embodying,r a housing;i l carrying therein laminated poles 2 vin a ring foi-m. About tlicseimles wound a. plurality olr tgroups oi" coils Il, el, 5, adapted to be connected to a three phase circuit. '.lhese coils have their axes extending inwardly to intersect each other and the core aXis, and the windings of these coils are at an angle to the plane of the series of the poles as well as at an angleto radii from the core to said poles.

Concentric of this housing l is disposed plunger 6 havingy a main or major laminated plunger or core portion 7 with a taper portion 8 providing` an air gap which is larger than that provided by an untapered core as to the poles 2 at the initial pull position for drawing this non-rotary core 7 trein its normal position of restinto the region oi' the transverse field developed by the annular series of longitudinally extending windings. The respective turns of the windings do not encircle the core 7, but are in'regons lying` between radial planes extending axially ot the core 7 The plunger 6- is connected by link 9 to lever 10, which as thus rocked is ollcctive through adjustable length link 1l, to :torce brake shoe levers l2, 13, tree oi" eletf'ator brake drum 14, against the resistance ei:

A base l? mayrarry the structure, and stop 18 mayv` be adjusted to limit the rocking of the lever lil. 'ihespriupy la accordingly normally acts lo hold Ilux core i' \\'ihdravvn i'roin thc re- `ion ol' the poles f2'.

rlhe magnetic pull oi the core 7 is non-rotary. 'l`he core movement is normal 'to the plane oll the coils. 'lhe successive coils in such a series are so wound as to establish a rotating lield. fis the plunger() is drawn to have its enlargement or core T niove into the field of the llux generated by the coils 3, 4, 5, the leakage is reduced and the air gap is incrca \d. the plunger Aets into central position the 'forces acting' upon it are balanced. There are no inductors carried by the plunger and the plunger in its design operates without any appreciable expenditure el' energjv tending' to establish torque. rlhe taper or reduction 8 in diameter oi the core i', while lengthening the air gap, also lessens the increase of the effective air gap area so that the increase in air gap area as the plunger is pulled into the core or stator which carries the coil, is out of direct proportion to the throw ot' said plunger.

rthe pull oi' this elect-romagnet is continuous due to the rotatingV eld. ccOrdingly, there no tendency to chatter, howl, or create other noise. ln i'acl the pull and holding action of 'this magnet is quiet even when compared with direct current magnets, with possibilities lor desirable design thereover. lllith the ordinary type of electroinapgnet and with the type 0i this disclosure with a straight cylindrical plunger and a straight cylindri-f cal stator, the pull initially is greater than with the tapered plunger. As in this pered construction the tapered portion "feniains in the inliuence of the eld, there is increase in the final holding pull over the linal holding` pull in the ordinary type of electron'iagnet and over the final holding pull in the straight cylindrical plunger and straight cylindrical core type of structure 0i this disclosure. rEhey curve 19 shows influence of the core. 7 with the taper 8 wherein the distance trai'led is shown as abscis sae and the pull is shov'n as ordinates (Fig.-

Sl, as compared with the curve 2O which H pull and distance characteristic S31-'erna net which the plunger The tapered portion 8 is approximately'lonly 25% of the portion 7 in the showing in Fig. 4. The taper can be made unii'orm for the full entrance of the core into the field, thereby taking the hump out of the curve 19 and producing curve 21.A

Instead of the normal concave curve 20, which isthe characteristic of the usual alternating current type of electromagnct, it

is possible to obtain a characteristic asl Shown by the curve l5) in the type o l' electromagnet as herein disclosed, or even down to constant straight line pull may be produced in a quiet alternating current magnet of the polyphase type. ln the lorm oi' the curve 19, there is thus simply produced a slowing up in the pull` action near the end of the stroke,pwhich may be of material worth, not only in taking shock oftl the structure and in quieting the brake operation, when a. brake is controlled, but this slowing up may be gaged as to the spring 15 so that this spring may approximate dash pot, comperation in receiving and neutralizing any hammer action adjacent the end of the plunger stroke.

The curve 2() is developed as from a non- -sealing operation, and the range of the core reciprocation may be, say from line 22 as outer limit of the stroke to line 23 against a stop. For a given magnet and voltage impreed, a' stronger spring may be installed, and the pullmay thusmore closely approximate neutralizing the spring action at the end of the stroke.

What is claimed and it is desired to secure by Letters Patent is:

1. The combination with a hollow core ot' windings disposed on said core, a polyphase electric current supply for the windings for the production ot a rotating magnetic field, and a plunger magnetized to eflect 4relative movement into position within said core, said windings having the planes of the wraps of said windings extending parallel to the line of direction of the plunger movement.

2. The combination with a hollow cylindrical core of windings disposed on said core.y a polyphase electric current supply for the windings for the production of a rotating magnetic field, and a plunger magnetir/.ed to be pulled into position within said cylindrical core providing a non-sealing air-gap between said plunger and core, said windings having the planes of the wraps of said windings extending parallel to the line of direction of the plunger travel. l

3. The combination with a hollow core of converging windings disposed on said core, a polyphase electric current supply l'or the windings for the production of a rotating magnetic field, and a. cylindrical plunger magnetized to effect relative pulling into position within said hollow core.

t. The combination of a magnetic core, a relatively non-rotating plunger, and a winding wound on said core for the production of a magnectic field for eilectingthrow between the core and plunger, said core and plunger being dissimilarly configured on their opposing magnetic faces to provide a variable air gap therebetween.

5. The combination of a magnetic core, a relatively non-rotating plunger, and an alternating electric current winding wound on said core for the production of a magnetic field for effecting throw between the core and plunger, said core and plunger pro viding in operative position a non-sealing variable air gap.

t5. The combination ot' a. magnetic core, a relatively non-rotating plunger, and a winding wound on said core for the production of' a magnetic field for effecting throw between the core and plunger, said core and plunger being provided with mounting and directing means in inoperative position determining an air gap distance therebetween and in operative position having .said same air gap distance as a maximum between the same core and plunger.

7. The combination of a magnetic core, a relatively non-rotating plunger, and an alternating electric current winding wound on said core lor the production of a magnetic field for effecting throw between the core and plunger, said core and plunger providing at a position of rest in operative position a variable air-gap extending in the direction of the line oil throw.

8. The combination with a magnetic core having converging poles having faces, ol a polypbase winding wound on said core for the Aproduction ot' a magneticy field, and a relatively reeiprocable non-rotating plunger magnetized to be moved along past portions of said pole. faces.

Sl. The method o'lI controlling a plunger to its core of' an alternating current solenoid having a tapered portion and a straight portion, which comprises establishing a rotating magnetic field by supplying a. polyphase current thereto. having the tapered portion within the influence ol' said field and the straight portion beyond the influence of said field when the plunger is in its inoperative position` and directing shifting to bring the plunger into a magnetically balanced position of' rest in said field.

10. The method of controlling movement between the plunger and core of an alternating current solenoid which comprises `establishing a rotating magnetic field between 'faces ot' said plunge;- and core. directing a plunger to increase effective air gap area as acted upon in traveling relatively into n said field. and modifying said vair gap ef-,'

fective area as determined by directly op posing faces of said plunger and core to 23 noti@ field :for eotmg throw lieto/*een dus core and plunger, said plunger having a maximum mzigneic elfl. position and clearance is to said core in the throw li action to, :it and beyond said position.

l2. Tho combination oi: a uuiguoic sore, :i relatively norrrotating plunger, amil am alernaing ororic current wixulin Wound on said core for the prmiluctiou ol u. magnetic: field for effecting throw bow-:oon lhs core and plunger, filiere being :au an' gap foetween said coro l and plunger ,ermiiingg lmlanced positioning olf said plunger in noufseuling position in said Held.

lll. The coml'iination of ma v miic coro, a relatively nonq'ozinfg i)lufiggrr7 und :in alternating); Qloorio curron \.'i1'1(li1i g wouiul on siiigl Coro for the producion of :i magi,- iie-ic, iolll for effecting throw between .s il @om mnd plunger, said Winding comprising u plurality of @A ng coil-i'uero boing an au* gap between faces of said com and plunger having in inoperlztim poisition an 'ectii'u area lea-mined by ilirectly op posing portions of suini faces7 which area is autom@ cally increased owarfl operativo position.

The combina/tion of a magnetic core, ai, relatively norrota'lziug plunger, and :in ulteifnatiiu.7 elecirio current winding wound on Suid Core for the production of a mag- Iwic field for effecting hrow between Said Core amlpluiigor, lierebeing an air gap bo ibween said com :mil plunger having oppos ing' faros in imperativi, position to provide :in ollemiw armi which is :iutonluticzilly iucra'ifxseifl toworil( operatve positions, Said increas@ iii area departing from direct pro por'iou with said; throw,

l5. The combination o1 ai magnetic coro having :m annular soi-@5 of radially directed polos, i polyplmse winding ou said poles for' ilu }Y=r()li1ci m oi' a` rotning' magnetic ',lfL :nul plunger mounted conceni-iically with the poles and in operative position. imi-iugzi taper fue@ opligosing said poles and spared all. ililferentdistances therefrom 3%. :i iliosiiion oi rest, lli@ greater Lliszznoe porimi eueriufg the field in throw operoion.

li: wit'iueem whereof l' alix my signature.

ERNEST B. THURSTON, 

